An organic light-emitting device (OLED) is a luminescent radiator by means of which electromagnetic energy is produced from electrical energy. Said device has an organic active layer in which the electromagnetic radiation is produced. The active layer is arranged between an anode and a cathode. When a conducting state potential is applied, the anode injects holes into the active layer as charge carriers, whilst the cathode injects electrons as charge carriers. The injected holes and electrons each drift (under the influence of an externally applied electric field) to the oppositely charged electrode and, on recombination, create an electroluminescent emission in the active layer.
An OLED has the advantage, in particular, of being able to be used as a large-area light source. For this purpose, the OLED should have the most even possible brightness (luminance) distribution over the active layer.